Ask Captain Lim

I am unable to find any latest news on this crash. Why are there no answers as this type of aircraft is still flying around? It is unusual to have a crash at an airfield and have all the evidence, as was this case, and still unable to solve the problem. I believe the captain is still not flying.       

Is it pilot error or computer failure? This is the most important question to be answered.

Hodson.

Hi Hodson,

I do agree with you that the public is still not very clear as to the exact cause of the Boeing 777 crash at London Heathrow on January 17, 2008.

The latest bulletin I got is the one issued by the AAIB here.  The gist of the answers are as follows:-

"The investigation revealed no evidence of an aircraft or engine control system malfunction. There is no evidence of a wake vortex encounter, a bird strike or core engine icing. There is no evidence of any anomalous behavior of any of the aircraft or engine systems that suggests electromagnetic interference.

The fuel has been tested extensively; it is of good quality, in many respects exceeding the appropriate specification, and shows no evidence of contamination or excessive water. Detailed examination of the fuel system and pipe work has found no unusual deterioration or physical blockages. The spar valves and the aircraft fuel boost pumps were serviceable and operated correctly during the flight.

The high pressure (HP) fuel pumps from both engines have unusual and fresh cavitation damage to the outlet ports consistent with operation at low inlet pressure.

The evidence to date indicates that both engines had low fuel pressure at the inlet to the HP pump. Restrictions in the fuel system between the aircraft fuel tanks and each of the engine HP pumps, resulting in reduced fuel flows, is suspected.

The focus of the investigation continues to be the fuel system of both the aircraft and the engines, in order to understand why neither engine responded to the demanded increase in power when all of the engine control functions operated normally. Under the direction of the AAIB, extensive full scale engine testing has been conducted at Rolls-Royce, Derby, and fuel system testing is ongoing at Boeing, Seattle."

So far, no operational changes are recommended by AAIB, Boeing or Rolls-Royce. Hence, the planes are not grounded but I believe they are all subjected to very thorough maintenance checks before being released for flight.

I am not sure whether the captain is still grounded unless it was due to pilot error. (He and his First Officer were honored as heroes in the crash). From the report, they did all they could after they discovered that the auto thrusts were not giving the required power as demanded by the computer.

Are the planes computers infallible?

Not necessary. On August 1, 2005, a Malaysia Airlines Boeing 777, en route from Perth, Australia to Kuala Lumpur was climbing past 38,000ft towards its cruising level when the flight crew were confronted with what the official report on the incident described as 'a situation that had previously been considered not possible'.

TimesOnline reported, "The autopilot pitched up the nose and the 777 climbed for 3,000ft, while the air speed dropped from 270 knots to 158 knots at which point the stall warning horn correctly sounded and the stick-shakers activated.

The pilot prevented disaster by disconnecting the autopilot and pushing the nose down. But then the auto throttle kicked in, commanding more thrust from the engines. The nose pitched up again and, of its own volition, the aircraft climbed another 2,000ft until it was brought under control."

The plane landed safely but, as the Australian Transport Safety Bureau report put it, the combination of a failed sensor and "a software anomaly" had created an "unexpected situation that had not been foreseen" and for which the crew had not been trained."

Could a similar electronic or computer fault have occurred on flight BA 038? The AAIB report was negative.

Please three of my related articles below:-

1. What went wrong with first crash of the Boeing 777!
2. Could the crash of the BA Boeing 777 be due to water in the fuel?
3. Could the FO of the Boeing 777 crash have extended his glide? 

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